One commonly used technique for repairing damage to roadways constructed of poured concrete is to cut out the damaged section and to replace it with a precast panel of the same dimensions. Usually the panel will be cast offsite, trucked to the site and then lifted into position. Typically the panel, which may weigh several tons, is lifted by the use of lifting anchors screwed into threaded inserts cast into the panel during its manufacture. Conventionally, the threaded inserts are in the form of internally-threaded collars which, after casting, open onto the upper face of the panel to receive the lifting anchors. For the several separate lifting operations likely to be involved between casting and laying of the slab in position, and likely involving storage of several panels in stacked relation and transportation of several panels in stacked relation, the lifting anchors will usually be required to be installed and removed several times. This can be quite a time-consuming and laborious operation as the thread length on the insert and which corresponds to the thread length of a threaded stem of the anchor runs for almost the full thickness of the panel.
At their lower ends the threaded inserts, although open, abut against a metal jacking plate, one for each insert, set into the underside of the panel during casting. After laying of the panel in position and removal of the lifting anchors, jacking rods are screwed into the inserts to engage the jacking plates which are in contact with compacted ground beneath the panel, in order to raise the panel so that it is set level with the surrounding roadway. During manufacture of the panel, grout holes are cast through the thickness of the panel at different locations over the surface of the panel and when the panel has been jacked into a position in which it is level with the surrounding roadway, concrete grout is injected through the grout holes to the underside of the panel in order to fill the void between the underside of the panel and the underlying ground surface. The jacking rods are removed from the threaded inserts after the grout has cured sufficiently to support the weight of the panel. As with the lifting anchors, because threaded engagement between the jacking rods and inserts occurs over a substantial thread length, it is a time-consuming and laborious operation to insert and remove the jacking rods.
Accordingly, there is a need to solve these problems.